Mankind may have walked on it, zoomed around it, and thrown satellites into its surface, but the moon still has her secrets. One of the mysteries that has perplexed scientists for quite a while has been mysterious milky white blotches on the moon’s surface that correspond with small magnetic fields that should be too weak to have any effect on the lunar soil. Now a group of scientists think they may have discovered the reason for the moon’s discoloration and understanding it could hold the key to keeping astronauts safe from radiation on long space flights.
While the Earth has a magnetic field that encompasses it, keeping us safe from the massive amounts of radiation that the sun can put out, our moon has no global defense against solar flares and cosmic rays. In a lot of areas, constant exposure to solar radiation has charred the lunar soil to a much darker shade of grey (not to be confused with the dark lunar maria that can be seen from earth which are the remnants of ancient lava plains). When scientists saw white blotches on the sun-baked surface that couldn’t be accounted for by lunar impacts, they had no idea what caused them until the Apollo program. With Apollo came the understanding that each of these white blotches were surrounded with extremely weak magnetic fields, fields so weak that they shouldn’t have any effect on the coloration of the surface. That mystery has remained for years, but a team looking into radiation shielding for spacecraft may have just figured out the answer.
Plasma physicist Ruth Bamford and her team have one of the most important jobs in spaceflight. They aren’t trying to build a better rocket or make sure the pilot’s seat has a cup holder in the right spot, they are trying to figure out how best to shield future astronauts from radiation during a long duration spaceflight. The principle problem with shielding space craft from radiation is that if you do it by using a physical barrier capable of deflecting the radiation it will almost certainly make the spacecraft too heavy to launch. The other, lighter method proposed for shielding is to create a magnetic bubble much like we have on Earth to deflect radiation, but the major problem with that is the vast amounts of energy needed to make it work. According to New Scientist, Bamford decided to breach this impasse by figuring out how the moon does it with weak magnetic fields.
Bamford claims that the moon is able to shield the small portions of its surface with such weak fields by using the radiation itself as a means for generating electricity. The negatively charged electrons flow along the field lines while the positively charged protons bust on through. The separation of charges in turn creates an electric field that is actually stronger than the magnetic field and pulls the protons back to the surface of the magnetic bubble where they slide off just like the electrons.
While it is a fascinating revelation for a long held mystery of the lunar surface and could be the key to making energy efficient radiation shields for spacecraft, Bamford and her team still don’t enough about the process to replicate it on a large scale. They successfully demonstrated the process in a lab using a stream of protons and electrons aimed at a small magnet, which easily deflected the particles, but covering a spacecraft in magnets could be just as weight prohibitive as any other type of physical shielding. They may still need to do some work to figure it all out, but it is a promising start.